Extruded flints and process for making same



United States Patent 12 Claims. b1. 15-152 This is acontinuation-in-part of application Serial No. I

623,798, filed November 23, 1956, now abandoned.

My invention generally relates to pyrophoric alloys and is moreparticularly directed to novel pyrophoric alloy compositions suitablefor extrusion.

Considered from another aspect, my invention is concerned with animproved and simplified process for the extrusion of flints frompyrophoric alloy compositions and with the flints obtained thereby.

While flints for use in cigarette lighters and the like were originallyproduced by casting methods, such flints have, in recent years,'bee nmanufactured by extrusion, as extrusion, of course, increases the plantoutput, simplifies the manufacture and may be carried out withconsiderably less expenditure than casting methods. Further, the generalquality of extruded flints including the pyrophoric characteristicscompare favorably with and are in many respects superior to that of castflints. For these reasons, the industry has generally adapted extrusionprocesses for the production of flints.

Extruded as well as cast flints consist essentially of cerium (mischmetal) iron alloys. However, those skilled in the art will readilyrealize that an alloy which may produce satisfactory flints by castingis not necessarily suitable as a raw material for extruded flints. Thisis so because the problems and considerations underlying the extrusionof flints are entirely different from those prevailing in castingmethods. In fact for many decades it was believed that the extrusion ofcerium (misch metal) iron alloys was not feasible and in this connectionI refer to my US. Patent 2,660,301 wherein I disclosed for the firsttime a commercially practical extrusion process for flint material andexplained the obstacles which have to be overcome.

However, although my basic invention as embodied in said US. patent hasbeen considered and proved to be a revolutionary advance in thisparticular art, the extrusion of flints from cerium (misch metal) ironalloys is still plagued by some serious problems. The most seriousditficulty in the manufacture of flints or flint rods by extrusion frompyrophoric cerium (misch metal) iron alloys resides in the extremelyhigh extrusion pressure which in present day processes is necessary forextruding the alloy composition through the extrusion die. Pyrophoricalloys used for the extrusion of flints ordinarily contain about 4.5 to40% of iron in addition to the cerium (misch metal) and such alloycomposition can only be extruded at pressures between 5,000 to 16,000kg. per square centimeter and at extrusion temperatures between 400-500"C. The particular pressure required is a function of the iron content inthe alloy and increases with increasing amounts of iron. It is obviousthat such high pressures require elaborate and excessively expensiveextrusion presses, which moreover are, of course, subjected toconsiderable wear and tear. As the extrusion tools have to be frequentlyreplaced and/or repaired, the intended gain and advantage by usingextrusion instead of casting methods is therefore considerably negatedor offset by the expenditure in apparatus. In this connection, I wish tostate that attempts have previously been made to reduce the extrusionpressure by alloying the basic alloy composi- 3,203,790 Patented Aug.31, 1965 ice tion with additional metals. Thus in my own US. Patent2,792,301 I have disclosed certain metals which under stated conditionsfacilitate the extrusion.

In the production of flints by casting as distinguished from extrusionit has been suggested to add appreciable amounts of copper or zinc tothe alloy mixture to increase the resistance of the flints todistintegration. Thus, US. Patents 2,408,400 and 2,389,198, for example,which are concerned with the production of flints by casting, recommendthat at least 1.2% of copper are added in addition to silver, nickel andchromium. I have carriedout extensive experiments'with this and otheralloy compositions intended for casting with a view of ascertainingwhether or not the teachings relating to the casting of flints could bebeneficially made use of for the purpose of reducing the workingpressure in the extrusion of flints.

' The results of my experiments are that these prior art castingcompositions containing copper, zinc and other metals cannot in fact beextruded and therefore do not contribute anything of value to theextrusion art and particularly have no bearing on the reduction of theextrusion pressure. For the purpose of substantiating this contention,the following should be considered: The extrusion of pyrophoric alloycompositions is by necessity carried out at temperatures at which thebillet or ingot to be extruded is in a plastic state. If the optimumextrusion temperature is abovethe melting point of one or several of themetals -of the alloy composition, this metal or metals liquify and theliquid phase seriously impairs the extrusion properuand in many casesrenders extrusion impossible. Thus, for example, I have attempted toextrude the alloy compositions disclosed in US. Patent 2,408,400 and2,389,198 previously referred to, but was not successful although Iincreased the extrusion pressure to 35 tons. The reason for my failurewas that the composition formed a substantial amount of liquid phasewhich soiled and blocked the extrusion tools of the press.

It is, accordingly, a primary object of this invention to provide for analloy composition which may be extruded at considerably lower pressuresthan was hitherto possible.

It is also an object of this invention to provide an extrusion processfor the extrusion of flint material which [may be carried out at lowerpressure values than heretofore.

Anoth r object of the invention is to provide extruded flints ofexcellent quality having superior pyrophoric characteristics.

Generally, it is an object of this invention to improve on the art ofextruding flints as hitherto practiced.

Briefly, and in accordance with this invention, 1' have ascertained thatthe addition of small amounts of copper wit-bin predetermined limitranges, to prior art extrusion alloy compositions considerablyfacilitates the extrusion procedure and permits the extrusion to becarried out at considerably lower pressure values than was hithertofeasible.

In my previous US. Patent 2,792,301, I have already suggested certainmeasures with a view to decreasing the required pressure for theextrusion procedure. Thus, in the prior patent referred to, I haveproposed to admix the basic alloy composition with metals such astitanium, cadmium, magnesium, calcium, aluminum, barium, zirconium orberyllium in predetermined quantities, i.e., 0.3% to 10%, preferably0.3% to 1%.

I have found that although the admixture of the elements referred to hasin many-instances a most beneficial influence on the reduction of theextrusion pressure, the "addition of such metals within the statedranges may somet1mes lead .to difliculties and is therefore undesired.This is so because some of the enumerated metals, erg. and zirconium,alloy with the basic cerium (misch metal)-iron composition only withdifficulty, particularly if amounts in excess of 0.3% are employed. Ifthe period for alloying the addition metals with the basic compositionis protracted, the composition has to be maintained in molten conditionfor relatively long periods which, of course, results'in metal losses.Further, some of the addi tion metals may adversely effect the corrosionresistance, shelf life and/or the pyrophoricity of the extruded fiints.

-In accordance with my present invention, I have con clusivelyestablished that small copper additions to the basic cerium (mischmetal)-iron alloy composition overcome the drawbacks referred to and yetsignificantly reduce the extrusion pressure, provided the copper isadded within a range of 0.05-0.45%

The following Table I clearly establishes the beneficial effect on theworking pressure of the addition of copper within the stated range.

*Not; extrudable because of partial liquefaction.

It will be noted that the extrusion pressure is 5100 kg./-cm. if thebasic alloy composition is lacking copper, While copper additions to upto 0.45% result in a significant pressure reduction.

Further, it should be emphasized that the upper limit of 0.45% of copperis critical as larger amounts of copper in alloy compositions cause apartial liquification of the basic alloy composition. This is indicatedin the table by test 47lb. In this connection I refer to my aboveremarks and also .to German Patent 891,824, Where this matter has beendealt within detail.

In analyzing the results of my tests as tabulated in Table I andconsidering the partial liquefaction of the alloy upon admixtures ofcopper in excess of 0.45%, I attempted to increase the copper content ofthe alloy while at the same time decreasing the extrusion temperature.As the partial liquefaction is, of course, dependent on the temperature,my reasoning was that a lowering of the working temperature would allow.me'to add larger amounts of copper without resulting liquefiaction. Theresults of my tests in this regard were, however, very discouraging.While I succeeded in extruding alloy compositions containing .up to0.90% of copper at a temperature of 440 C., ie. a temperature which is40 C. lower than that of Table I, the extrusion pressure again rose to aconsiderable extent. My tests in this respect are tabu- *Not extrudablebecause of partial liquefaction.

In comparing the results of Tables I and II it will be observed that,for example, a copper content of 0.90% requires an extrusion pressure of4300 kg./cm. at 440 C., while the corresponding pressure is only 2100kg./cm. at 480 C. if the copper content is 0.45%. Therefore, the uppercopper limit of 0.45% is critical if the extrusion pressure is to bereduced. In this connection it will be realized that from a practicalpoint of view the reduction of the pressure is more desirable andimportant than a reduction in the working temperature.

According to another embodiment of my invention, I have ascertained thata further addition of one or several of the metals titanium, magnesium,calcium, beryllium, barium, aluminum and zirconium is efiective furtherto reduce the extrusion pressure and to improve the quality of theextruded fiints, provided these metals are added in minute quantitiesnot exceeding 0.3%. Thus, if, for example, the basic ceriurn (mischmetal)-iron composition is alloyed with 0.05-0.45% of copper and 0.2% oftitanium or zirconium, the extrusion pressure is still further reduced.

Tests in this respect are tabulated in Table III.

TABLE III Composition of alloy in percent by Extrusion weight pressurein kg./cm. Test No. at 480 C. Cerium Additional and after (misch Fe Cuelements 30 minutes metal) of preheating treatment 80. 2 19. 6 0.20% Mg4, 800 80. 05 19. 5 0. 21 0.24% Mg" 3, 000 79. 19. 8 0.25% Al 4, 900 79.92 19. 6 0. 25 0.23% Al- 2, 900

The invention will now be described in connection with a specificexample, it being understood, however, that this example is given by wayof illustration and not by way of limitation, and that many changes maybe performed Without departing in any way from the scope and spirit ofthis invention as recited in the appended claims.

Example 1 This example illustrates test 471a of Table I above. An alloycomposition comprising 80.25% by weight of cerium (misch metal) and19.3% of iron was alloyed with 0.45 of copper and cast into-billet oringot form. The alloy billet was thereafter heated to about 480 C. for30 minutes and the billet was inserted into an extrusion press and wasextruded into thin rods of 2 to 6 mm. diameter at an extrusion pressureof 2100 kg. per square centimeter. The extruded rods were thereafter cutdown into individual flints of suitable length.

As control, the test was repeated with an alloy ingot which did notcontain the copper addition. Extrusion only took place at a workingpressure of at least 5100 kg. per square centimeter at the sametemperature (see test 468a).

Similar tests were carried out to arrive at test results 469, 470, 471and 4711;.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What I claim is:

1. A pyrophoric alloy composition suitable for extrusion essentiallyconsisting of about 4.5 to 40% of iron and 0.05 to 0.45% of copper, theremainder being cerium (misch metal).

2. An extruded flint essentially consisting of about 4.5 to 40% of ironand about 0.05 to 0.45 of copper, the remainder being cerium (mischmetal).

3. An extruded flint essentially consisting of about 18 to 22% of ironand about 0.05 to 0.45 of copper, the remainder being cerium (mischmetal).

4. A pyrophoric alloy composition suitable for extrusion essentiallyconsisting of about 4.5 to 40% of iron,

0.05 to 0.45% of copper, and a minute quantity of at least one metalselected from the group consisting of titanium, magnesium, calcium,beryllium, barium, aluminum and zirconium, said quantity being less than0.3%, the remainder being cerium (misch metal).

5. An extruded flint essentially consisting of about 4.5 to 40% of iron,0.05 to 0.45 of copper, and a minute quantity of at least one metalselected from the group consisting of titanium, magnesium, calcium,beryllium, barium, aluminum and zirconium, said quantity being less than0.3%, the remainder being cerium (misch metal).

6. An extruded flint essentially consisting of about 18 to 22% of iron,0.05 to 0.45 of copper and a minute quantity of at least one metalselected from the group consisting of titanium, magnesium, calcium,beryllium, barium, aluminum and zirconium, said quantity being less than0.3%, the remainder being cerium (misch metal).

7. A process of producing flint rods by extrusion which comprisesextruding a pyrophoric alloy in ingot form and essentially consisting ofabout 4.5 to 40% of iron and 0.05 to 0.45% of copper, the balance beingcerium (misch metal) at a temperature of about 400 to 500 C. and at thelowest working pressure at which extrusion is possible.

8. The process as claimed in claim 7, wherein the alloy is preheatedbefore being extruded.

9. The process as claimed in claim 7, wherein the extrusion pressure isabout 2100 and 3500 kg./cm.

tionally contains a minute quantity of at least one metal selected fromthe group consisting of titanium, magnesium, calcium, beryllium, barium,aluminum and zirconium, said quantity being less than 0.3%, theremainder being cerium (misch metal).

11. In a process of extruding flints from alloy compositions in ingotform, wherein the alloy composition essentially consists of about 4.5 toof iron, the remainder being cerium (misch metal), and the alloycomposition is extruded at a temperature of about 400-500 C., theimprovement which comprises incorporating into the alloy composition,prior to extrusion, 0.05 to 0.45 of copper to reduce the requiredextrusion pressure.

12. A process as in claim 11, wherein the alloy composition additionallycontains a minute quantity of at least one metal selected from the groupconsisting of titanium, magnesium, calcium, beryllium, barium, aluminumand zirconium, said quantity beng less than 0.3%, the remainder beingcerium (misch metal).

References Cited by the Examiner UNITED STATES PATENTS 2,408,400 10/46Kent -152 2,792,301 5/57 Bungardt 75135 X FOREIGN PATENTS 1,017,507 10/57 Germany.

A DAVID L. RECK, Primar Examiner. 10. A process as in claim 7, whereinthe alloy addi- 30 y

1. A PYROPHORIC ALLOY COMPOSITION SUITABLE FOR EXTRUSION ESSENTIALLYCONSISTING OF ABOUT 4.5 TO 40% OF IRON AND 0.5 TO 0.45% OF COPPER, THEREMAINDER BEING CERIUM (MISCH METAL).